1. Field of the Invention
The present invention relates to a method of manufacturing a device by which a wafer having devices formed in a plurality of regions demarcated by planned dividing lines formed in a grid pattern on the face-side surface of the wafer is divided along the planned dividing lines into individual devices and an adhesive film for die bonding is attached to the back-side surface of each of the devices.
2. Description of the Related Art
In a semiconductor device manufacturing process, for example, it is a common practice to form devices such as ICs (integrated circuits) and LSIs (large-scale integrations) in a plurality of regions demarcated by streets (planned dividing lines) formed in a grid pattern on the face-side surface of a substantially circular disk-shaped semiconductor wafer, and to divide the regions with the devices formed therein along the planned dividing lines, thereby manufacturing the individual devices. As a dividing apparatus for dividing the semiconductor wafer, a cutting apparatus generally called dicing apparatus is used. The cutting apparatus has a cutting blade about 40 μm in thickness, by which the semiconductor wafer is cut along the planned dividing lines. The devices divided in this manner are packaged and put to wide use in electric apparatuses such as cellular phones and personal computers.
An adhesive film for die bonding, which is formed from an epoxy resin or the like in a thickness of 70 to 80 μm and is called a die attach film, is attached to each of the individually divided devices, and each device is bonded to a device-supporting die bonding frame through the adhesive film by heating. In an exemplary method for attaching the adhesive film for die bonding to the back-side surface of the device, the adhesive film is adhered to the back-side surface of the semiconductor wafer, and the semiconductor wafer is adhered to a dicing tape through the adhesive film. Thereafter, the adhesive film together with the semiconductor wafer is cut by a cutting blade along the planned dividing lines formed on the face-side surface of the semiconductor wafer, to form the devices each of which has the adhesive film attached to the back-side surface thereof (refer to, for example Japanese Patent Laid-open No. 2000-182995).
However, when the adhesive film is adhered to the back-side surface of the wafer and the resulting assembly is cut by the cutting blade, the devices thus cut apart may show irregular motions on the adhesive film. Particularly, in the case where the thickness of the wafer is as small as 100 μm or below, the devices may be broken by the shock of the cutting blade which is rotating at a high speed.
In order to solve such a problem, the present applicant has proposed, in Japanese Patent Application No. 2007-70000, a method of manufacturing a device wherein after an adhesive film is adhered to the back-side surface of a wafer and the adhesive film side is adhered to the surface of a dicing tape, the wafer is irradiated with a pulsed laser beam, which has such a wavelength as to be absorbed in the wafer, from the face side of the wafer along planned dividing lines, so as to divide the wafer into individual devices and to cut the adhesive film.
This approach, however, has the following problems. When the wafer is irradiated with the pulsed laser beam having such a wavelength as to be absorbed in the wafer from the face side of the wafer along the planned dividing lines, thermal energy would be concentrated on the irradiated region with the result of generation of debris, and the debris would adhere to device surfaces, thereby lowering the device quality. In addition, when the wafer is divided by irradiation with a laser beam, the divided surfaces would be denatured, resulting in that the individually divided devices show a lowered transverse rupture strength.